The aim of this study was to investigate the influence of extremely low-frequency electromagnetic fields (ELF-EMFs) on mast cells (MCs), parafollicular cells, and nerve fibers in rat skin and thyroid gland. The experiment was performed on 24 2-month-old Wistar male rats exposed for 4h a day, 7 days a week for 1 month to EMFs (50 Hz, 100-300 microT, 54-160 V/m). After sacrifice, samples of skin and thyroid were processed for indirect immunohistochemistry or toluidine blue staining and then were analyzed using the methods of stereology. The antibody markers to serotonin, substance P, calcitonin gene-related peptide (CGRP), and protein gene product 9.5 (PGP) were applied to skin sections and PGP, CGRP, and neuropeptide Y (NPY) markers to the thyroid. A significantly increased number of serotonin-positive MCs in the skin and NPY-containing nerve fibers in the thyroid of rats exposed to ELF-EMF was found compared to controls, indicating a possible EMF effect on skin and thyroid vasculature.